Apparatus for producing edge compression stresses in metal strips



Sept. 13, 1955 LIEICEIRWOO 2,717,626

- .L. APPARATUS PROD NG EDGE MPRESSION SSES IN ME ST I S STRE FiledMarch l9 1 N V EN TOR. fi/K/W? A ffla/zvaad Wm M United States PatentO 12,717,626 APPARATUS FOR PRODUCING EDGE COM- PRESSION STRESSES IN METALSTRIPS Glenn L. Sherwood, Benton Harbor, Mich., assignor of one-third toHenry L. Johnson and one-third to Ferdinand J. Thar, Benton Harbor,Mich.

Application March 9, 1951, Serial No. 214,748

6 Claims. c1. 1s3-32 This invention relates to improvements in methodand apparatus for producing compression stresses in the edges of anelongated flexible metal strip and stock produced thereby.

The main objects of this invention are:

First, to provide an apparatus for producing compression. stresses inthe edges of an elongated metal strip whereby the strip is renderedsuitable for the forming of slats for Venetian blinds and the like andmay be cross sectionally curved or conformed and the shape thereof ismaintained without twist or camber.

Second, to provide an apparatus for producing compression stresses inthe edges of an elongated flexible metal strip which does not result inthe disfiguring or substantial marring of the surface of the strip.

Third, to provide a method of producing compression stresses in theedges of an elongated metal strip resulting in a strip which is welladapted for use as stock in the forming of Venetian blind slats and thelike of curved or other nonplanar cross section.

Fourth, to provide a strip of rolled metal stock suitable for use in theforming of Venetian blind slats and like parts.

Objects relating to details and economies of the invention will appearfrom the description to follow. The invention is pointed out in theclaims.

A preferred embodiment of the invention is illustrated in theaccompanying drawing, in which:

Fig. 1 is a fragmentary side elevational view of an apparatus embodyingmy invention and well. adapted for the practicing of the method of myinvention.

Fig. 2 is an enlarged fragmentary view looking from the right of Fig. 1and partially in vertical section on a line corresponding to line 22 ofFig. 3.

Fig. 3 is a fragmentary view in section on a line corresponding to line3-3 of Fig 2.

Fig. 4 is a plan view of a strip of thin metal stock to be processed.

Fig. 5 is a plan view of the processed stock or stock after it has beenpassed through the apparatus of my invention.

Fig. 6 is an edge view thereof.

In the accompanying drawing 1 represents the stock to be treated orprocessed to produce compression stresses in the edges thereof, 100 thestrip after processing with the bulges or distortion 101 thereinresulting from the compression stresses produced in the edge of thestrip by passing the stock through the apparatus. It will be understoodthat the distortions 101 between the edges,as illustrated, are verygreatly exaggerated and they are shown as being alternately and. quiteuniformly disposed; and while they usually are more or less uniformlydisposed the metal strip illustration is for the purpose of illustratingthat the edges of the strip have compression stresses set up therein andthat there is no longitudinal stretching of the center portion of thestrip.-

The numeral 2 represents the roll of stock and 3" the roll of stockafter processing.

The apparatus illustrated is especially designed for use in theproducing of stock suitable for use in the making or formingof slats forVenetian blinds; As an. example, the strip of stock may be cold rolledsteel 2" wide by .008 thick. This is a dimension or approximatedimension suitable for Venetian blinds such, for example, as are2,717,626 Patented Sept. 13, 1955 used in homes. The apparatus may beused for the processing or treating of wider and thicker stock for slatsand other uses but in that case, the dimensions of the parts areincreased to correspond with the width of the stock treated.

The apparatus of the embodiment illustrated comprises a suitable base 4which may be bolted or otherwise secured to a table or bench and whichis provided with spaced bearing uprights 5 provided with bearings 6 forthe spindle 7 of the pulley 8. The spindle 7 rotates freely in thehearings or if preferred, the pulley 8 may rotate on the spindle. Thepulley 8 is crowned and provided with guide flanges 9 at its ends. Thestrip of stock 1 is passed or translated around the pulley with asubstantially U-shaped bend, the guide pulleys 10 and 11 being arrangedso it is guided to and around the pulley to form the U-shaped bight 12therein which is in supported engagement with the center of the crown ofthe pulley as is shown in Figs. 1 and 3.

The means for winding the stock on the spool 13 or the brake means forthe spool 14 of the supply roll 2 are not illustrated but it is desiredto point out that only suificient tension on the strip is required tokeep the bight 12 of the U-bend of the stock in taut or close supportingengagement with an arc of the pulley. As the strip is translated aroundthe pulley, the bight portion 12 thereof is transversely bent and thecentral part thereof urged against the crown of the pulley by means ofthe shoelike supporting members 15 which have curved work supportingedges 16, desirably inwardly beveled. The work engaging faces of thesemembers 15 are disposed at a radial distance from the axis of the pulleysubstantially less than the radius of the pulley at the center of itscrown but the surfaces 18 are spaced from the pulley so that the edgesof the strip are not clamped against the pulley but are supported indiverging relation to the surfaces of the pulley as is shown in Fig. 2.

The members 15 are mounted on a support 17 pivoted at 171 at one side ofthe pulley 8 and adjustably supported by the screw 19 which engages thebase and is provided with a handwheel 20 for convenience in adjustment.With this arrangement, the portion of the strip passing around thepulley is transversely conformed as shown in Fig. 2. This results inproducing compression stresses in the edges of the flexible strip whichadapts it for use in the forming of various parts but as stated, it isparticularly adapted as stock for the forming of Venetian blind slatsand also Venetian blind slats of curved or other nonplanar crosssection.

The strip treated is not subjected to stretching or other stresses whichsubstantially distort or tend to distort the granular structure thereofbut compression stresses are produced in the edge portions sufficient toprevent or minimize twisting distortions when the treated stock isformed into Venetian blind slats or the like. As stated,-

the only sufiicient longitudinal stress or tension is required on thestrip of stock 1 to translate it around the pulley and keep itsufiiciently taut to maintain it in supported engagement with asubstantial arc of the crowned pulley. The treated or processed stock isnot transversely curved as is the portion illustrated, passing aroundthe pulley in an operative relation to the members 15 but issues fromthe apparatus substantially flat, but may be subjected to treatment byknown means to remove camber if that is deemed desirable.

I have illustrated and described my inventionin a simple but practicalembodiment thereof and in an apparatus that may be usedin the practicingof my method. I have not attempted to illustrate more completemechanisms which might be desired in commercial production as it isbelieved that this'disclosure will enable'those skilled in the art toembody or adapt my invention as may be desired.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is:

1. An apparatus for producing compression stresses in the edges of anelongated resilient metal strip comprising a supporting frame, a crownedpulley journaled on said frame for free rotation, means for guiding andtranslating a metal strip endwise around said pulley in a longitudinallycurved form With a portion of the strip intermediate its edges ininteriorly supported engagement with the crown of the pulley and withedge portions of such longitudinally curved portion of substantial widthprojecting laterally beyond such interiorly supported intermediateportion of the strip and being interiorly unsupported, and exteriorsupport members for such interiorly unsupported edge portions of thestrip mounted on said frame for adjustment relative to the axis of thepulley and having curved work engaging faces in exterior supportedengagement with interiorly unsupported edge portions of the stripthroughout a substantial arc of the bend thereof, the work engagingfaces of the support members being spaced a radial distance from theaxis of the pulley substantially less than the radius of the pulley atthe work engaging surface thereof so that edge portions of a substantialarc of the longitudinally curved portion of the strip supportedly engagesaid support members and the strip is transversely curved simultaneouslywith the longitudinal curving thereof resulting from its translationaround the pulley.

2. An apparatus for producing compression stresses in the edges of anelongated resilient metal strip comprising a supporting frame, a crownedpulley journaled on said frame for free rotation, means for guiding andtranslating a metal strip endwise around said pulley in a substantiallyU-bent form with a portion of the U-bend intermediate its edges ininteriorly supported engagement with the crown of the pulley and withedge portions of the U-bend of substantial width projecting laterallybeyond such interiorly supported intermediate portions of the strip withsaid edge portions interiorly unsupported, and exterior support membersfor such interiorly unsupported edge portions of the strip mounted onsaid frame for adjustment relative to the axis of the pulley and havingbeveled work engaging faces in exterior supporting engagement With theinteriorly unsupported edges of the strip throughout a substantial arcof the bend thereof and so that a substantial arc of the interiorlyunsupported edge portions of the U-bent portion of the strip lappinglyengage the said faces of said support members and the U-bent portion ofthe strip is transversely curved simultaneously with the longitudinalcurving thereof resulting from its translation around the pulley.

3. An apparatus for producing compression stresses in the edges of anelongated resilient metal strip comprising a supporting frame, a pulleyjournaled on said frame for free rotation, means for guiding andtranslating a metal strip endwise around said pulley in a substantiallyU-bent form with a portion of the U-bend intermediate its edges ininteriorly supported engagement with the peripheral face of the pulleyand with edge portions of the U-bend of substantial width projectinglaterally beyond such interiorly supported intermediate portion of thestrip with said edge portions interiorly unsupported, and exteriorsupport members for such interiorly unsupported edge portions of thestrip mounted on said frame for adjustment relative to the axis of thepulley and having curved beveled work engaging faces in exteriorsupporting engagement with the interiorly unsupported edges of the stripthroughout a substantial arc of the bend thereof so that a substantialarc of the interiorly unsupported edge portions of the U-bent portion ofthe strip lappingly engage said support members and the U-bent portionof the strip is transversely curved simultaneously with the longitudinalcurving thereof resulting from its translation around the pulley.

4. An apparatus for producing compression stresses in the edges of anelongated resilient metal strip comprising a supporting frame, a pulleyjournaled on said frame, means for guiding and translating a metal stripendwise with a central portion thereof curvedly bent around and ininteriorly supported engagement with a substantial arc of the pulley andwith edge portions of the strip of substantial Width out of contact withthe pulley and projecting laterally beyond said interiorly supportedportion of the strip and being interiorly unsupported, and laterallyspaced exterior support members for the interiorly unsupported edgeportions of the strip adjustably mounted on said frame and havingoutwardly curved faces engaging edge portions only of the strip inlaterally spaced relation to the portion of the strip in interiorlysupported engagement with said pulley, the curved faces of said exteriorsupport members being spaced a radial distance from the axis of thepulley substantially less than the radius of the strip engaging portionof the pulley, the edge portions of the strip being urged upon the saidexterior support members only by the inherent resilience of the stripresulting from the transverse curving of the arcuate portion thereofwhile in interior supported engagement with the pulley.

5. An apparatus for producing compression stresses in edge portions ofan elongated metal strip comprising a supporting frame, a crowned pulleyrotatably mounted on said frame, means for guiding and translating thestrip around said pulley with an intermediate portion of the strip ininteriorly supported engagement with the pulley and longitudinallycurved around a substantial arc thereof and with edge portions of thestrip of substantial width interiorly unsupported for free flexingradially of the pulley, and exterior support members for said interiorlyunsupported edge portions of the strip adjustably mounted on said frameand having curved work engaging surfaces spaced laterally from the workengaging are of the pulley and in exterior supported engagement withsubstantial arcs of the interiorly unsupported edge portions of thework, the work engaging surfaces of said exterior support members beingspaced a radial distance from the axis of the pulley substantially lessthan the radius of the pulley at the work engaging crown thereof.

6. An apparatus for producing compression stresses in edge portions ofan elongated metal strip comprising a supporting frame, a pulleyrotatably mounted on said frame, means for guiding and translating thestrip around said pulley with an intermediate portion of the strip ininteriorly supported engagement with the pulley and longitudinallycurved around a substantial arc thereof and with edge portions of thestrip of substantial width out of contact with the pulley and interiorlyunsupported for free flexing radially of the axis of the pulley, andexterior support members for said interiorly unsupported edge portionsof the strip mounted on said frame and 1: having arcuately curved workengaging surfaces spaced laterally from the Work engaging arc of thepulley and in exterior supported engagement with substantial arcs of theinteriorly unsupported edge portions of the work,

n the work engaging faces of said exterior support members being spaceda radial distance from the axis of the pulley substantially less thanthe radius of the pulley at the work engaging surface thereof.

References Cited in the file of this patent UNITED STATES PATENTS135,150 Pearce Jan. 21, 1873 471,407 Westaway Mar. 22, 1892 902,031White Oct. 27, 1908 1,032,907 Hyde July 16, 1912 1,937,663 Norton Dec.5, 1933 1,963,724 Taylor June 19, 1934 2,076,458 Hall Apr. 6, 19372,156,163 Pierce Apr. 25, 1939 2,263,540 Johnson Nov. 18, 1941 2,600,442Stanius June 17, 1952

